Tealium’s best practice is to load all tags Asynchronously. This post will outline how to follow the Tealium best practices when implementing Optimizely.
- For an understanding of the trade-offs between Asynchronous and Synchronous loading of testing tools see this [POST](https //community.tealiumiq.com/t5/Testing/Key-Considerations-when-performing-A-B-Testing/m-p/2087).
- For options to implement Optimizely synchronously see this [POST](https //community.tealiumiq.com/t5/Testing/Optimizely-Synchronous-Implementation/m-p/2108).
There are two methods of implementing the Optimizely Asynchronous tag. The content of your site and your testing requirements will determine which approach to use. It is recommended that you try the two methods in the order they appear in this post.
NOTE: Both methods assume the
utag.js file is coded asynchronously on the page.
Method 1 (RECOMMENDED): Bundle Optimizely Async Tag and load on all pages
This method is recommended because the tag will not block anything else from loading in the page.
Step 1: Enable the Bundling feature for Tags that will load on all pages.
- Click Save/Publish in the top-right corner.
- Click Configure Publish Setting. Then scroll down to Performance Optimization settings.
- Turn ON the Bundle Tags Loading On All Pages toggle. This will bundle the Tag with
utag.js, thus reducing the number of network calls made by the browser.
STEP 2: Add and set up the Optimizely Async Tag
This Tag is available in Tealium’s Tag Marketplace, which is home to a large selection of vendor Tags. Click here to learn how to add a Tag to your Tealium iQ profile.
Here are the steps to set it up:
- Enter your Project ID. This is the number at the end of the script tag Optimizely sends you.
- Select Wait Flag = No from the Advanced Settings list.
- Proceed to the Load Rules tab and check the default Load on All Pages rule.
- Proceed to the Data Mappings tab and map the destinations you wish to send data to. Click here to learn how to map a data source to a Tag destination.
If you plan to track E-Commerce data with the Async Tag, we recommend that you use the E-Commerce Extension to automatically map that data.
|Destination Name||Destination Variable||Description||E-Commerce Extension Mapping (RECOMMENDED)|
||Project identifier provided by Optimizely||N/A|
||Unique identifier assigned to the order||
|Revenue in Cents||
||Subtotal amount (in cents) of the order||
||Name/Type of conversion event
Default event is
STEP 3: Save/Publish your profile.
IMPORTANT: For the Async Tag to fire as soon as possible, make sure the
Method 2: Run Optimizely as blocking Tag
Optimizely typically prefers to be synchronous on the page so it can run “sooner” and determine the test before other stuff (like your Analytics tool) runs. However, the only way to have Optimizely run soon enough and still be asynchronous is by serving its
.js library from an alternate location. In doing so, the Optimizely Async Tag becomes a blocking Tag and any subsequent asynchronous scripts (for example,
utag.10.js) will not load until the blocking Tag is complete.
Make sure to upgrade the
utag.js version if you are not already using the latest (see utag.js Release Notes).
- Repeat step #2 above to add and set up the Optimizely Async Tag.
- Drop down the Advanced Settings and enter the location of the
.jslibrary in the Custom Script Source field.
- Save/Publish your profile.
That’s it! A few simple differences, but this will dramatically change the way the Optimizely file is loaded and how other tags are loaded after Optimizely.
Thank you for your feedback!
This page was last updated: April 7, 2016